Minimum oxygen cost of human walking with geometrically similar leg movements

The mechanism by which the expenditure of oxygen to walk per unit distance at an intermediate speed is minimized, by definition optimal walking, was investigated to characterize optimal walking in humans with variations in individual walking speeds. Oxygen uptake and step rate（SR）were measured among 7 young male subjects walking at an increasing speed from 16.7 to 131.7 m min−1 with 5 m min−1 increments every 1 min on a level treadmill. Measurements of leg length（L）were also made and step length（SL）was calculated by dividing walking speed by SR. The hip joint angle（θ）was calculated as a function of both L and SL such that θ＝2sin−［1 SL（／ 2L）］ deduced from a mathematical geometrically similar model of pendulum−like legs. The minimum oxygen cost to walk per unit distance for each subject was observed over a wide range of speeds from 60 to 100 m min−1.However, the oxygen cost of walking for all the subjects was minimized during a step cycle through a hip−joint angle of about 46 deg in the astride position, regardless of L. The stifflegged model demonstrated that the pathway of the trunk during optimal walking with a swing leg angle of 46 deg was approximately maintained at an even level by the counteracting effects of the leg decline and the heel rise. These results suggest that the minimum oxygen cost of transport during optimal walking was achieved by the mechanism underlying the maximum interchange between the gravitational−potential and kinetic energy for the body with an even level of the trunk that reduces extra muscular work needed against internal and external resistance, as well as against gravit

M-Theory Phenomenology and See-Saw Mechanisms

A version of M-theory phenomenology is proposed in which the symmetry is based on the group $SO(10) \times SO(10) \times SO(10) \times U(1) \times U(1)$. Each SO(10) group acts on a single generation. The $U(1) \times U(1)$ is regarded as the hidden sector symmetry group. The supersymmetry is broken in the hidden sector by the Fayet-Iliopoulos $D$-term for each group. The $D$-term is needed also to circumvent the powerful non-renormalization theorem since the $SO(10) \times SO(10) \times SO(10)$ is broken down to the usual SO(10) by the pair condensation of certain messenger sector multiplets. The exchange of U(1) gauge bosons gives an attractive force for the pair to be created and condensed. The off-diagonal mass matrix elements among the generations in these messenger sector multiplets are the source of the flavor dynamics including the CP violation. The pair condensation of another multiplet in the messenger sector leads to the doublet-triplet splitting. The SO(10) decuplet Higgs couples only to one of the generations. The other couplings should, therefore, be calculated as higher order corrections. We present our preliminary results on the calculation of the mass matrices and the mixing angles for leptons and quarks in this model.Comment: 19 pages, 16 figures, Talk given at Neutrino Mass and See-Saw Mechanism, Fujihara Semina

Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano-Micro-Macro Trans-Scale Design

Semiconducting nanomaterials with 3D network structures exhibit various fascinating properties such as electrical conduction, high permeability, and large surface areas, which are beneficial for adsorption, separation, and sensing applications. However, research on these materials is substantially restricted by the limited trans-scalability of their structural design and tunability of electrical conductivity. To overcome this challenge, a pyrolyzed cellulose nanofiber paper (CNP) semiconductor with a 3D network structure is proposed. Its nano-micro-macro trans-scale structural design is achieved by a combination of iodine-mediated morphology-retaining pyrolysis with spatially controlled drying of a cellulose nanofiber dispersion and paper-crafting techniques, such as microembossing, origami, and kirigami. The electrical conduction of this semiconductor is widely and systematically tuned, via the temperature-controlled progressive pyrolysis of CNP, from insulating (1012 ω cm) to quasimetallic (10-2 ω cm), which considerably exceeds that attained in other previously reported nanomaterials with 3D networks. The pyrolyzed CNP semiconductor provides not only the tailorable functionality for applications ranging from water-vapor-selective sensors to enzymatic biofuel cell electrodes but also the designability of macroscopic device configurations for stretchable and wearable applications. This study provides a pathway to realize structurally and functionally designable semiconducting nanomaterials and all-nanocellulose semiconducting technology for diverse electronics.Koga H., Nagashima K., Suematsu K., et al. Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano-Micro-Macro Trans-Scale Design. ACS Nano, 16(6), 8630-8640, 2022. https://doi.org/10.1021/acsnano.1c10728

Cellulose nanofiber paper as an ultra flexible nonvolatile memory

On the development of flexible electronics, a highly flexible nonvolatile memory, which is an important circuit component for the portability, is necessary. However, the flexibility of existing nonvolatile memory has been limited, e.g. the smallest radius into which can be bent has been millimeters range, due to the difficulty in maintaining memory properties while bending. Here we propose the ultra flexible resistive nonvolatile memory using Ag-decorated cellulose nanofiber paper (CNP). The Ag-decorated CNP devices showed the stable nonvolatile memory effects with 6 orders of ON/OFF resistance ratio and the small standard deviation of switching voltage distribution. The memory performance of CNP devices can be maintained without any degradation when being bent down to the radius of 350 μm, which is the smallest value compared to those of existing any flexible nonvolatile memories. Thus the present device using abundant and mechanically flexible CNP offers a highly flexible nonvolatile memory for portable flexible electronics.Nagashima, K., Koga, H., Celano, U. et al. Cellulose Nanofiber Paper as an Ultra Flexible Nonvolatile Memory. Sci Rep 4, 5532 (2014). https://doi.org/10.1038/srep05532

Effect of Age on the Human Ability to Identify Fragmented Letters through Visual Interpolation(視覚内挿を通じて断片文字を同定する能力に対する年齢の影響)

雑誌掲載版人間は不完全な文字の同定など視覚内挿にたけている。加齢がこの能力にどのような影響を与えるかを調べるため、20〜76歳の健常者56名の断片文字の同定能力を調べた。アルファベットの断片文字を無作為にパソコンの画面上に表示した。断片文字は無作為に完全な文字から削除できる矩形域(約4×8ピクセル)に作製した。断片文字読解スコアは全対象において、ピクセル50%削除での適正同定は80%以上であったが、適正同定スコアはピクセルの70%、80%、90%削除で有意に減少し、これは男女間或いは年齢間で大きな差異はなかった。断片文字同定能力は健康な高齢者では良好に維持されており、認識機能(言語能力)のある側面を評価するのに利用できると考えられ

Comparison of Blood Flow Velocity in the Middle Cerebral Artery between Men and Women at Rest and during Exercise(男性及び女性の安静時及び運動時における中大脳動脈血流速度の比較)

雑誌掲載版若い健常男性10名と女性10名に6分間の自転車運動を実施させ、血圧及び中大脳動脈血流速度(MCA V)を連続測定した。これらの値は安静時にも測定し、男女差を調べた。その結果、平均MCA V値は男女とも安静時に比べ運動時に有意に増加した。女性の平均MCA V値は安静時、運動時とも男性に比べ有意に大であった。女性の運動時における平均血圧は男性よりも有意に低値であったが、安静時の平均血圧には男女差を認めなかった。女性のMCA V値が高値であるのは動脈血酸素量が相対的に低いことを代償しており、男性とほぼ同じ量の酸素を血流から組織に効率的に輸送するのに重要と考えられた

Economical Estimates of Oxygen Uptake as a Function of Gait Parameters for an Ambulatory Monitoring System (携帯式モニタリングシステムのための歩行パラメータ関数としての酸素摂取量の実用的予測)

雑誌掲載版酸素摂取量(VO2)、歩行速度、歩数及び歩幅の関係を示す経験式を得る目的で、健康若年男性7名を対象に、水平トレッドミル上で16.7m/分から131.7m/分まで毎分5mの割合で加速歩行、106.7m/分の5分間歩行から毎分5mの割合で16.7m/分まで減速歩行させ、その間のVO2及び歩数を記録し、更に歩く速度と歩数から歩幅を算出した。歩行速度に対するVO2の変化は緩徐な加速と減速の間のVO2応答の平均値によって算出でき、運動テストを時間と費用の面で改善できることが示された。VO2予測値は歩行速度の関数として正確に二次方程式によって示され、更に歩数と歩行速度との密接な関係を用いれば、VO2もまた歩数の関数として表すことが可能である

All-nanocellulose nonvolatile resistive memory

Celano, U., Nagashima, K., Koga, H. et al. All-nanocellulose nonvolatile resistive memory. NPG Asia Mater 8, e310 (2016). https://doi.org/10.1038/am.2016.144

Paper-Based Disposable Molecular Sensor Constructed from Oxide Nanowires, Cellulose Nanofibers, and Pencil-Drawn Electrodes

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in ACS Applied Materials and Interfaces, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acsami.9b01287